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7 plied, it too may be rendered brittle so that a mar s'rrss PROCESS OF RECLAIMING WASTE LEATHER.

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No Drawing.

T 0 aZZ whom it may concern Be it known that I. JOHN KnaRsLnY MIT- oHELL,'of Rosemont, Pa, have made certain new and useful Improvements in a Process perature above the boiling point of water and then dried, the leather will be rendered so brittle that it may be readily pulverized while the vegetable matter, which in the case of old shoes may comprise cotton linings and linen thread, will not be unduly affected, so that such material together with any metal that may be present can be separated from the pulverized leather by the use of a sieve. v

Apparently the water or steam used serves several purposes. F or one thing vegetable matter will stand a considerably higher degree of heat when wet than when dry; so that the water may be said to protect the vegetable matter; also the water makes it more easy to distribute the heat uniformly to the waste leather, and likewise the water seems to have some action in helping to render the leather brittle. The leather, however, will become quite hard if no water is used and of course old shoes can be heated without the use of steam, but if no means of protecting the vegetable material is supseparation from the leather will be almost impossible.

In carrying out my invention, the degree of heat used may vary within wide ranges, for both heat and time are factors. That is, the lower the temperature the longer the time of treatment that is reqired. For example, if the old shoes are treated at a temperature of about 215 F., ordinarily many hours will be required to give complete results, whereas at a temperature of about 260 F. the leather will be so changed in from one to two hours that it will be brittle when dry. Accordingly I recommend a temperature in excess of 240 F., however the temperature to be used may be varied to suit the operator,

Specification of Letters Patent.

Patented Oct. 18, 1%21.

7 Application filed December 15, 1919. Serial No. 345,039.

to give the greatest economy considering both the fuel consumed and the time necessary.

An example of commercial operation of my process is as follows: A quantity of'old shoes were soaked in cold water for about twelve hours to remove the dirt and also to saturate the leather and cotton. These shoes were then drained and put in a digester such as is used in the rubber reclaiming industry and treated with live steam at a gage pressure of about fifty pounds for one hour; that is, they were treated for this length of time at a temperature of about 260 F. At the end of this treatment the shoes were thoroughly dried and then placed in a tumbler and rotated with blocks of wood. The tumbler was provided with screens around its circumference, the screens having a mesh of about one half inch. As this tumbler was rotated the leather which had been rendered exceedingly brittle by the heat treatment, was all broken up by the wooden blocks, and passed through the screen together with the metal such as nails, fasteners and eyelets. This treatment was continued until the cotton linings and the linen thread used for stitching were left practically free from leather. Of course, a certain amount of metal will be left in this tumbler, held by the linings and shoe strings.

The products remaining in the tumbler can be recovered by well known processes; the metal, the linen thread and the cotton may be separated by hand and the cotton rags may be washed and reclaimed in the usual manner applicable to such articles.

The leather and metal which pass from this tumbler were placed in a ball mill and there treated until the leather was substantially pulverized. After this was done the leather was separated from the metal by the use of a screen. It is possible to reduce the leather to an almost impalpable powder, but

this is not usually necessary. It is enough that the leather be reduced to a size smaller than any of the metal parts. The leather so obtained may be put to various uses, for example, it may be used in the production of ammonium sulfate by appropriate chemical treatment. The metal will have a scrap value particularly the brass, from which the iron and steel nails can be separated by a magnetic separator. Of course if it is not considered worth While to separate the metal from the broken up leather, this last step may be omitted.

It is to be understood that the foregoing description is only given as an illustration of one method by which my process may be carried out and that the same may be modified in many particulars without departing from the spirit of my invention.

What I claim is:

V 1. The process of reclaiming waste leather from articles containing leather and vegetable components, which comprises the steps of heating the leather sufficiently to render it brittle when dry While preventing substantial injury to the vegetable components, breaking up the leather while in the dry state and mechanically separating the broken up leather from other components of the articles treated. V

2. In the process of reclaiming Waste leather, the steps of treating the waste in the presence of steam at a temperature in excess of 240 F. until the leather is so changed that it will be brittle when dry,(lrying the leather, breaking it up, and separating it from other components of the waste.

3. In the process of reclaiming waste leather the steps of treating the Waste in the presence oi steam at a temperature of about 260 F. for about one hour, drying the leather, breaking up the dry leather, and

separating it from other components of the waste.

J. KEARSLEY MITCHELL. Y 

